Russian Accused of Hacking U.S. Technology Firms Is Extradited

PRAGUE — A Russian man accused of hacking the systems of three American technology companies in 2012, possibly compromising the personal information of more than 100 million users, was extradited to the United States from the Czech Republic on Friday.

The man, Yevgeniy A. Nikulin, appeared in Federal District Court in San Francisco after arriving in the city around 6 a.m. He pleaded not guilty to the charges against him. Magistrate Judge Jacqueline Scott Corley scheduled his next court appearance for next week.

“This is deeply troubling behavior once again emanating from Russia,” Attorney General Jeff Sessions said in a statement. “We will not tolerate criminal cyberattacks and will make it a priority to investigate and prosecute these crimes, regardless of the country where they originate.”

Mr. Nikulin had been held in the Czech Republic since the authorities there arrested him in 2016. His case quickly turned into a battle between Washington and Moscow over whether he should be tried in the United States.

He was arrested just two days before the Obama administration formally accused the Russian government of stealing and disclosing emails from the Democratic National Committee and other institutions and prominent individuals.

In fighting Mr. Nikulin’s extradition to the United States, his lawyer had argued that the case against him was politically motivated. The Russian government argued separately that it had jurisdiction in the case after a Moscow court issued an arrest warrant for Mr. Nikulin in November 2016 in the 2009 theft of $3,450 via a website called WebMoney.

More broadly, the Kremlin claims that the United States has unfairly targeted Russians around the world for political purposes. The Russian ambassador in Prague has said the case against Mr. Nikulin was an effort to “extend the jurisprudence of American law to the territory of third countries.”

This year, Spain extradited to the United States two Russians suspected of hacking. Another Russian, Aleksandr V. Vinnik, is being held in Greece pending extradition requests from Washington and Moscow.